Although steroids perform many important functions, the controlling mechanisms governing the biogenesis and secretion of steroids are not yet well understood, and information is virtually unavailable concerning the nuclear-cytoplasmic interactions in adrenal cell function. We propose to study these processes using techniques developed in my laboratory for producing reciprocally reconstructed cells (i.e., the fusion of a steroidogenic nucleus to a nonsteroidogenic cytoplasm and a nonsteroidogenic nucleus fused to a steroidogenic cytoplasm). These reciprocally reconstructed cells will be treated with adrenocorticotropic hormone (ACTH), a hormone known to stimulate adrenal steroid secretion, and the loss, acquisition, or retention of steroidogenic function will be analyzed. Based on our preliminary results, we will focus our attention on the role of tubulin in the control of steroidogenesis. Our preliminary data suggest that tubulin in a previously undescribed form is associated with the ability of a cell to produce steroids. It is anticipated that the results from these experiments will increase our understanding of the controlling mechanisms of steroidogenesis.